Co-doping of Ho–Yb ion pairs modulating the up-conversion luminescence properties of fluoride phosphors under 1550 nm excitation

In this study, up-conversion fluoride phosphors NaY1-x-y-m-nMxF4:Er3+y,Ho3+m,Yb3+n (M = Lu3+/Gd3+) were synthesized by a low-temperature combustion method. The optimal ionic ratios in the matrix lattice were also determined by a controlled variable method. It was confirmed that doping a small amount of Ho3+ ions and Yb3+ ions in the Er-doped sample matrix lattice can form a mutual sensitizer and a transient energy capture center to enhance the sample's up-conversion luminescence under excitation at the 1550 nm band, respectively. It was also found that the lanthanide ion introduced can modulate the red-to-green ratio of the up-conversion luminescence of the sample. The phase composition and morphology of phosphors were investigated using X-ray diffraction and scanning electron microscopy. The up-conversion luminescence mechanism of Er-Ho-Yb tri-doped samples excited at the 1550 nm band was also investigated. This work presents a novel approach for improving up-conversion luminescence with high color-purity phosphors for display lighting applications when excited at 1550 nm.